Widespread demolition, beefed up structural requirements and strict planning rules have dictated how new Christchurch buildings look, says a leading local architect.

Designs for new Christchurch buildings often attract a negative reaction, with many complaining they are unimaginative glass boxes.

Canterbury chairman of the New Zealand Institute of Architects David Hill said it was not a surprising response.

"Change is easier to handle when it's small and gradual, but of course the change to the fabric of our city has been big and sudden."

New structural codes, the loss of hundreds of buildings and the new city plan all influence a building's final shape, he said.

"The changes since the earthquakes have been very dramatic. It has been very sudden and it will take people time to get used to it. It is a big change."

He said it was hard to design a building for an empty site in a largely demolished street.

"At this stage, some of these buildings are the first off the rank and you are building the first piece of a street. Instead of replacing a rotten tooth, you are building the first tooth.

"Previously, you had neighbouring buildings and were able to relate your new building to them in better ways. When you lose so much built history it is hard."

Hill said many clients now wanted much stronger buildings with exposed structural elements like steel beams.

"The structures have become much more robust and architects are expressing the structure more. There is a feeling that the building occupiers will feel safer being able to see those structural elements.

"Previously, buildings were designed around people getting out safely and the building would sustain damage and it was either repairable or not. Now, most building owners don't want to be in that situation. They want to build something that is quake-resilient."

Barnaby Bennett, who is writing his PhD on transitional architecture in Christchurch, said the rebuild so far was "very conservative".

"I am not impressed so far. We have fallen back into a conservative mode. The danger is we rebuild a very conservative city that doesn't do anything brave. We will look back in 20 years and see we missed an opportunity.

"You can do more adventurous things affordably and that is where we are failing. It is creating quite a dull outcome."

Bennett said Christchurch should hold more international design competitions to attract exciting ideas from around the world. Hill will speak at a public lecture on Christchurch building design at CPIT on Thursday, June 20, at 6pm.